Category: Physics Blogs

Do you want to bring a big surprise to your teachers, parents and friends by scoring amazing marks in Physics exam?

Here are some tips!

Have you been branded as a slow learner or a weak students in Physics so far?

Do you fear of failure in Physics in the forthcoming examination?

Is Physics a nightmare to you?

Not any more !

Religiously follow these guidelines and you will be astonished by the results.

These are a set of instructions with proven track record

Caution!!!

These are not intended for students who score more than 90%, but for those students who score less than 40%. This will help the students to score more than 60 – 80% depending on how much you are able to follow the directions.

Following the guidelines will help you prepare yourselves to score more with a few days of hard work!

Electricity is the most widely used form on energy because it is most efficiently distributed and transported. Also it can be easily converted to other forms of energy like mechanical energy, heat energy etc. Also since it is one of the fastest forms of usable energy it is used in logic digital circuits for computation since it gives the fastest results. It is this versatility of electricity that makes it so useful for modern life.
Of course electrical energy has various forms as well. It can be stored charge, alternating current or direct current. Each of these forms of energy have different advantages. Now we know that most of power that we get in our homes is in the form of AC. However it is not necessarily the most used form of energy. In fact most electronic equipment use DC power and converts AC from the supply to DC. Then why is it made AC in the first place. Let us discuss that shall we?

As the world’s fossil fuels are continuously depleted with increasing use we run the risk of facing a shortage soon enough in the future. Alternatives are a must as we already face the heat here in India with capping of LPG cylinders. One of the biggest consumers of fossil fuels are petroleum-based vehicles. Whether it is a diesel car or a petrol car or a CNG vehicle it doesn’t really matter. They all use fossil fuels which are bound to run out one day or the other. We need to continuously improve current efficiencies of transportation vehicles while still improving on alternative energy sources. One of the biggest solutions to alternative energy solutions are using hydrogen instead of carbon based fuel as an energy source.

Hydrogen as a fuel has a lot of potential to be used as energy because it not only releases a large amount of energy when burnt but it also prevents the release of toxic fumes as pollutants.

Let’s do a little bit of math shall we?

I promise it won’t be too large.

Bond energies of hydrogen

The bond energy of the hydrogen bond is 103 kcal/mole. And the bond energy of the hydrogen oxygen bond is 110 kcal/mole. Also the oxygen molecule has 116 kcal/mole of energy.

Therefore the energy released on formation of the water molecule requires breaking one oxygen molecule and two hydrogen molecules first.

That would mean the energy required = 2 x 103 + 116 = 322 kcal/mole

But when water is formed the energy released is = 4 x 110 = 440 kcal/mole

Hence the net energy gain = 440 – 322 = 118 kcal/mole

And this simple math shows the huge amount of energy which is gained on burning hydrogen as a fuel. If a human being were to be powered up by a hydrogen engine he would run 52 miles on just 1 litre! Hydrogen based cars can theoretically provide mileage as good as 93 miles per gallon which is still much better than gasoline based cars providing 35 miles per gallon.

This picture shows exactly what the components of the hydrogen economy consist of.I won’t talk about all the boring points in detail but only some of the parts which are really interesting.

Production and delivery

Hydrogen has a huge source in the form of our vast oceans and seas which provide an ample source of hydrogen. The problem is converting the water to hydrogen which requires energy in the first place.

Well right now they use natural gas and other petroleum products as well as biogas to produce hydrogen. Yes production is actually the biggest hurdle to the hydrogen economy. Hydrogen requires huge amounts of energy to be produced.(It only makes sense since it produces a huge amount of energy on combustion as well.) People are actively working on getting hydrogen to be obtained from a safe source. There are many technologies like aluminium based production (still waiting to be patented) for effective hydrogen production.

And yes there are several hoaxes doing the rounds around the internet which claim to have made super efficient methods to obtain hydrogen from water and hence make cars that run miles on just plain water!!! Well NASA itself has yet to make such a breakthrough but of course there is no giving up hope as people are still trying.

Although I am optimistic that this can be effectively taken care of using solar , wind , hydel power and various other renewable energy sources(like i told you before the future depends on all energy renewables working together) Then the hydrogen can be transported using storage tanks to fuel stations where the vehicles can refill their tanks!

And no I am not talking about science fiction. This is reality as industries work to implement these systems into the current economy.

Fuel cells

This is the talk of the town when it comes to hydrogen based economy. Fuel cells use a continuous supply of hydrogen to be directly converted to energy using a chemical reaction. This means efficiencies are quite high when using a fuel cell to power up a vehicle as compared to using internal combustion engines to power up a car.

There is huge money in the R&D for fuel cells in the automobile sector.There have been lots of hydrogen based fuel cells which are running commercially as well. Although there has been electric vehicles which have been shown to have much higher efficiencies they lack the power or speed pick up of fuel cell based cars and car maniacs out there swear by top speeds and revving pick up.

Storage

Now this is a real tricky issue hydrogen is the lightest of all elements out there and it is easily the least dense of all gases. In fact 1 gram of hydrogen would occupy as much as 22.4 litres! that too at 0 degrees celsius. Not too good when considering that we would need more than that to provide decent mileage to the vehicles. Well scientists have been looking for ways to combat this dilemma.

One of the ways include in-situ production of hydrogen.

It means the hydrogen would not be carried directly as a fuel. Instead hydrogen containing compounds would be used to generate the hydrogen at the time of running the car. However this method reduces efficiency significantly and renders the use of the vehicle as useless!

Another one of the methods include storage of hydrogen in a really efficient way

This means nanotechnology again! Yes the use of carbon nanotubes to store hydrogen has been deemed a potentially powerful method to store huge quantities of hydrogen in the vehicles. That however is a costly method and current research includes making hydrogen storage even cheaper.

Safety?

Now this is a bit of a tricky issue because hydrogen is even more susceptible to combustion than petroleum. Although that also means that fires breaking out won’t produce toxic fumes but then again they will bring out a bigger bang if they accidentally catch fire. Also current hydrogen storage techniques are not exactly 100% leak proof which means the dangers of accidents are higher! However this can be offset by using standards and protocols to enhance the safety factor of using hydrogen.

So what’s the real problem in implementation of hydrogen as a potential energy source?

Well this again lies in costs. Changing equipment and technology that has been built on petroleum will cost huge amounts and also current petroleum-based vehicles and fuel rates are cheaper than those of hydrogen based ones. Of course this should rapidly change in the very close future. In fact there are many companies already that provide hydrogen cars and hydrogen refuelling outlets.

Gravity, one of the four main fundamental forces in nature. It is one of the most commonly observed forces in nature and yet it is as still one of the least understood of all forces.

Gravity was brought into fame by this famous apple shown above when it garnered enough strength and weight to detach itself from the tree and land on Newton’s head. This triggered his brain cells into thinking what made the apple fall down and thus Newton penned the theory of gravity.
The formula of gravity as given by him was:
And although he made the theory of gravity in a real short while it took him
twenty years to publish it in his book.Why? Because he had to prove that the mass of an object lies at it’s centre and for that he had to develop calculus to such a point that this could be proved. So in a way that apple was responsible not only for the discovery of the theory of gravity but also the the development in the field of calculus.
But why did newton have to prove that the mass lies at it’s centre?

Take a look at the above picture. Now if you see the formula you would see that given no action of any external forces the two bodies would attract each other with the force that is inversely proportional to the square of the distance between them. But what is the exact distance between them. Because mass can be distributed over a large volume. So if the two bodies touched each other the force of gravity is supposed to be infinite right? Because the surface has mass and the mass is at zero distance from each other. Well that’s what the mass being concentrated at it’s centre means. The force of gravity is taken by calculating the distance between the centres of gravity of two continuous volumes of masses. That way no matter how close or how small or heavy the objects are they would never make the distance zero. Think about it!!

This theory was an absolute success as it was a unifying concept that not only explained the free fall of apples towards the earth but also the movement of the planets around the sun and the movement of galaxies and stars!

Of course the problem was that nobody including Newton actually understood what gravity was!They knew it was a force but the origin or the behaviour of this force still remains unknown.That’s when Einstein made his epoch making theory of special relativity and also the general theory of relativity.
Einstein made a simple observation. He already found that nothing can exceed the speed of light from all frames of reference via his theory of special relativity. Then he put up a thought experiment. He supposed that the sun would suddenly disappear. In that case the force of gravity keeping the earth in it’s orbit around the sun would just disappear too. But the light from the sun takes 8 minutes to reach the earth. So in that case we would still see the sun and yet we would not feel it’s gravity. That leads to the conclusion that the effect of gravity reached the earth faster than the speed of light! But nothing can travel faster than the speed of light. This apparent contradiction led him to modify the theory of gravity a bit. While there was nothing wrong with the magnitude of gravitational force it was the way the gravitational force lines acted that was changed.
Einstein said that gravity was the effect of bending the geometry of the space around it that led to the observation of a force acting.

Look at the above diagram. Suppose the the black line represents the path along which it is possible to move also called a dimension.
If we move both one will travel in a straight line while the other will travel in a bent line. If the lines become invisible it will seem as if the the object on the straight line is under no force but the object moving on the curved line is being pulled by a force that is changing it’s direction.

This is exactly what einstein called it. He said gravity bends space in such a way that it seems like a force.His theories were tested and proven multiple times and they were almost always found to be true. He was truly a remarkable genius since he explained a fundamental force through geometry!

Now fast forward to the present we have new theories called standard model, string theory etc. However they still find explaining gravity a mystery! Yes what is gravity has been found but what explains it’s origin is still a mystery! While the world might be rejoicing at finding the higgs boson the boson does not explain gravity. And though string theory does predict it , the theory itself is yet to be verified by the scientific community.

Of course nowadays newer more expensive equipment are being created which sought to find the elusive particle of gravity called gravitons. And hopefully we will fully gain an in-depth understanding of gravity one day. Maybe one day the unknown apple shall fall on someone’s head again and we shall be saved from the ignorance of that special force called gravity!

I am sure solar energy requires no introduction. Today India is being rocked by issues like the Nuclear proliferation treaty, coal scam etc. These are primarily because of the impending energy crisis that the world will come face to face with soon enough. And India is going to be one of the worst affected as it is one of the most densely populated countries. We recently got a glimpse of what might happen when fossil fuels get exhausted when there was a massive grid failure in the northern parts of the country. It was because of the fact that some of the states drew more than excess power that caused the generators to slow down thus disrupting the entire grid. It exposed the country’s dependence on fossil fuels only and the impending need to promote renewable energy sources. Sadly our policy makers are not too concerned with tapping alternative energy sources while all efforts to do so(nuclear power) is met with opposition for petty politics.However there are plenty of other sources as well. While hydel power is a prospective source of energy in India it is consequential because it can damage fragile ecosystems and displace entire populations. Then naturally Solar energy seems to be the logical choice.
So what’s stopping them from adopting solar energy?
Two things:
a) Cost
b) Erratic supplya) Cost
Yes like any other new product in the market costs determine how effectively it can be implemented. The biggest problem with solar energy is that it is very expensive. Yes it takes about 2000$ just to install solar Photovoltaic(PV) modules plus even in the well developed sunny states of the U.S. the cost of solar cells is about 0.11$ / kWh. Now that really is expensive if you compare it in the Indian currency.b) Erratic supply
Yes it is true that India has a huge amount of solar radiation input being in the tropics and everything working out to be fine India should be having more than enough energy to compensate for the energy needs of the country. BUT we should also try to remember that India is a place where the monsoons cover the Indian skies with clouds for a considerable part of the year too. This does deter the energy supply and this would have been a cause of great distress among the millions as energy demands are high and an uninterrupted supply is necessary in many parts of the country. Plus supply during the night time would be a huge problem as there is no effective way to store energy obtained during the day.
But what exactly is a photovoltaic cell?
A photovoltaic cell uses photons from the sun’s energy spectrum and converts it into kinetic energy of electrons.
It has an antireflective coating at the top to remove any sort to prevent loss of solar energy by reflection. As can be seen from the diagram, The photons strike the electrons at the junction of the p type and n type semiconductors to create a voltage difference. This voltage causes a current to flow in the closed circuit.
If solar energy needs no investment other than maintenance to continue then why should the initial high cost be a problem?
Well the problem comes from the fact that efficiency of solar PV cells is very small. Typical energy efficiencies are about 8 to 10% today. In fact all the major corporations of the world are working on increasing efficiencies as you read this article.
As you can see the technology used increases efficiency a lot. But what is not mentioned here is that the cost of increasingly complex technology is quite high. Efficiency determines the fate of new technology as solar pv cells are no exception.
But that does not mean that solar energy does not hold promise. For it has been calculated that the amount of solar radiation the earth receives at the sea level is more than enough to supply 8 times the energy requirements of the World’s population.

Black holes-Not exactly Black!!Now we have known black holes as giant swirling holes present in the universe which are known to swallow anything that comes close to it. Yes we have had countless rumors and fantasies about black holes being warps in time , a portal to another dimension and the doorway to a mirror world. Of course black holes don’t really do something like that but that doesn’t mean they are not fascinating by themselves.The mystery of black holes has fascinated physicists, scientists and certainly many others alike with their mysterious behavior. Their birth, evolution etc. are still under study and are the objects of obsession of most astrophysicists. So If it’s not a portal to the next dimension then what is it and where do the objects that it pulls inwards disappear to?Well think of it this way. You may have heard of how when a body of mass m and another mass M attract each other with a force given by F=G.M.m r2And the fact because of this force the potential energy that exists between them is P.E. = G.M.m rAnd also the fact that escape velocity can be found by equating it with kinetic energy of the object to be equal to it’s potential energy K.E.= 0.5 m.v2 Now equating the kinetic energy with the potential energy we get v2 =G. m rNow imagine a mass with gigantic (and i really mean it) mass and really tiny radius such that G.M =c2 rwhere c is the speed of light.Yes that’s what black holes exactly are. They are objects having mass and sometimes having charge as well as angular momentum such that any object on it will have to travel at the speed of light just to escape. So that explains why all objects cannot escape the gravitational pull of a black hole. Is it that strong?Well it is so strong that it is known to even absorb light. That’s right! Black holes actually bend gravitational space around it so much that even light cannot escape it’s pulling power. Scientists have named this as the infinite space time curvature!! At this point the state of the system is called singularity. In the state of singularity the some of Einstein’s equations along with some other big equations give weird solutions the details of which i will not bore you with. But what i will say is that any mass near this point of singularity will have time running down slower for it!(Time travel theories anyone?!!)Why are scientists so obsessed with it? Well for one thing they hold vital clues as to the origin of the universe. It’s true. The requirement of the formation of black holes is gigantic mass and small radius. That was the condition of the universe just a few moments before and after the big bang. So when that small point exploded in the event of the big bang many black holes were formed as the universe was expanding. So the black holes we study including the one at the centre of our galaxy is a by product of the big bang. So we can actually figure out where it all began!So how are they formed?Well like i told you the big mass and small radius is a good condition for the formation of black holes. So lots of black holes were formed after the big bang. Also lots of black holes are formed when massive stars collapse due to their own gravitational pull. But of course once formed it doesn’t stay together forever. It slowly decays by means of a radiation called Hawking’s radiation.So where do these masses disappear into?Well that is something no one is sure of! Yes that’s true. Nobody really knows what happens to all that sucked up mass. While it is true that a lot of the mass is emitted as energy from the accretion disks. In fact accretion disks are some of the brightest stuff in the universe. Not so black any more right?But scientists have found that this energy emitted as energy does not equal the energy obtained from the mass energy equivalence (any one remember Einstein’s epoch changing equation? e=mc2) energy obtained from the mass swallowed. (Though it is more efficient than fusion or fission as they use of 0.4% of the mass to be converted to energy while accretion disk formation uses 40% of the relative rest mass!)In fact information is lost inside the black hole. It would have been ok if black holes existed forever but the fact is they don’t. They decay through hawking’s radiation and hence it seems that the information is truly lost. In quantum mechanics this is the same as violation of conservation of energy!So next time your physics teacher tells you that nothing violates the conservation of energy you might wanna raise your hand and ask him/her about black holes. If he is genuinely interested in learning he will certainly try to help you explain better.